For this problem, it is best to just dissect it into its component parts. One needs to know what the chemical structure is for phosphoric acid, the propyl group, and a propyl ester.

Phosphoric acid has the chemical formula H3PO4. It contains 3 hydrogen atoms, 1 phosphorous atom, and 4 oxygen atoms. Within the provided attachment, a possible structure for the dipropyl ester of a phosphoric acid has been drawn to show how these atoms are bonded to a central phosphorous atom. 1 oxygen atom is double-bonded to the central phosphorous atom whereas 1 0H and 2 0CH2CH3 groups are bonded to this central phosphorous atom. The propyl group and propyl ester have been identified within the provided figure.

Keep in mind that the figure that is provided is just one figure having a specific stereochemistry as well as retaining the H atom. There are other possible representations.